On addition of $1 \ mL$ solution of $10 \% \ NaCl$ to $10 \ mL$ gold sol in the presence of $0.025 \ g$ of starch,the coagulation is just prevented. What is the gold number of starch?

The product$(s)$ formed when $H_2O_2$ reacts with disodium hydrogen phosphate is

The product $\begin{array}{*{20}{c}} {CH_2 - O - COCH_3} \\ {|} \\ {CH_2 - O - COCH_3} \end{array}$ is obtained by the reaction of which of the following?

In a book of $500$ pages,it is found that there are $250$ typing errors. Assume that Poisson law holds for the number of errors per page. Then,the probability that a random sample of $2$ pages will contain no error,is :

$A$ coil of $50$ turns and $4$ cm radius carries $2$ $A$ current. The magnetic field at its centre is ...... mT.